Acid mist mitigation agents for electrolyte solutions

ABSTRACT

Sulfonate-, sulfate-, or carboxylate-capped, alkoxylated anti-misting agents having the structure: R((AO) n X) m ((AO) n H) p , and methods of suppressing mist from electrolyte solutions by adding a mist-suppressing amount of one or more compounds selected from the group consisting of compounds of the Formulas R((AO) n X) m ((AO) n H) p  and R 3 N + (CH 3 ) 2 R 4 , and mixtures thereof, to electrolyte solutions.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a divisional of U.S. patent application Ser. No.12/166,372, filed Jul. 2, 2008, which is a continuation-in-part ofpending U.S. patent application Ser. No. 11/857,473, filed Sep. 19,2007, which claims the benefit, under 35USC119, of U.S. ProvisionalApplication Ser. No. 60/828,389, filed Oct. 6, 2006, the entire contentsof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to the control of mist formation aboveelectrolyte solutions during processes, such as the electrowinning,electroplating, and electroforming of metals, in which apotentially-hazardous mist is formed.

2. Background and Related Art

Electrowinning is the process by which metals are recovered from aqueouselectrolyte solutions resulting from the extraction of the metal ionfrom an acidic or basic leach solution. It is frequently employed in therecovery of metals, such as copper, from the respective metal-containingores, wherein the leaching, solvent extraction, stripping andelectrowinning of metals from their ores have many of the same commonunit operations or steps. These steps frequently include: (1) the metalvalue(s) in the mined and crushed ores being converted to anacid-soluble form, possibly by an oxidizing roast or a reduction; (2)ores from step (1) being leached, such as with an aqueous solution of astrong acid, usually sulfuric acid, to form an aqueous acid leachsolution of pH 0.9 to 2.0, containing the desired metal ion andrelatively small quantities of other metal ions (impurities that must beremoved prior to final recovery of the desired metal(s)); (3) theresulting metal(s)-pregnant aqueous acid leach solution being mixed intanks (possibly with one or more repetitions in order to improve metalrecovery and/or to separate desired metal value(s)) with an extractionreagent, such as an oxime or mixture of oximes, that is/are selectivefor the desired metal(s), and dissolved in a water-insoluble,water-immiscible organic solvent, to form a metal-extractantcomplex/chelate that is separated from the metal(s)-depleted aqueousphase in, e.g., a settling tank; (4) the metal-loaded organic phasebeing then mixed (again, possibly, with one or more repetitions) with ahighly-acidic strip solution (e.g., concentrated sulfuric acid), whichbreaks apart the complex, dissolving the metal ions into another aqueoussolution that, following another phase separation from thenow-metal-depleted organic phase, is customarily forwarded to anelectrowinning “tankhouse”; and (5) in the tankhouse, the metal valuesare deposited on the cathodes by electrodeposition and then recoveredfrom those cathode plates. Other processes may be employed with othermetals, such as nickel, zinc, and the like, in order to produce anelectrolyte from which their respective metal values may be electrowon.

It is during the electrowinning (electrodeposition) stage that an acidicmist is often generated above the electrolyte (strip aqueous phase).This mist is a result of small bubbles of oxygen being generated at theanode, while the metal is plating out at the cathode, and when thesebubbles rise to the top of the electrolyte solution and break, smallparticles of acidic electrolyte are shot into the air, resulting in anacidic mist.

Electroplating is the process of applying a metallic coating to anarticle by passing an electric current through an electrolyte in contactwith such article. The ASTM adds a quality restriction by definingelectroplating as electrodeposition of an adherent metallic coating onan electrode such that a surface, having properties or dimensionsdifferent from those of the basic metal, is formed.

In the electroplating process, the metals or metalloids (nonmetals thatare semiconductors, e.g., arsenic, germanium, and the like, which may beelectroplated in the same manner as metals), being used may be presentin the aqueous compositions in metallic form and/or in an anionic form,and may be one or more of zinc, nickel, copper, chromium, manganese,iron, cobalt, gallium, germanium, arsenic, selenium, ruthenium, rhodium,palladium, silver, cadmium, indium, tin, lead, bismuth, mercury,antimony, gold, iridium, and/or platinum. In addition, many alloys, suchas brass, bronze, many gold alloys, lead-tin, nickel-iron,nickel-cobalt, nickel-phosphorous, tin-nickel, tin-zinc, zinc-nickel,zinc-cobalt, and zinc-iron, even lead-indium, nickel-manganese,nickel-tungsten, palladium alloys, silver alloys, and zinc-manganese,are also electroplated commercially.

Another type of electrodeposition in commercial use is a composite form,in which insoluble materials are codeposited along with theelectrodeposited metal or alloy to produce particular desirableproperties. Polytetrafluoroethylene (PTFE) particles are codepositedwith nickel to improve lubricity. Silicon carbide and other hardparticles, including diamond, are co-deposited with nickel in order toimprove wear properties or to make cutting and grinding tools.

The essential components of an electroplating process are an electrodeto be plated (the cathode); a second electrode to complete the circuit(the anode); an electrolyte containing the metal ions to be deposited;and a d-c power source. The electrodes are immersed in the electrolyte,such that the anode is connected to the positive leg of the power supplyand the cathode to the negative. As the current is increased from zero,a minimum point is reached where metal plating begins to take place onthe cathode.

Plating tanks are formed from materials which are either totally inertto the plating solution or are lined with inert materials in order toprotect the tank. For alkaline plating solutions, mild steel materialsare used. For acid plating solutions, other materials are used,depending on the chemical composition of the plating bath, such astitanium and various stainless steel alloys, polytetrafluoroethylene,KARBATE® impervious graphite, HASTALLOY® nickel alloys, zirconiumalloys, and the like.

The plating tanks are fitted for d-c power, usually with round copperbusbars, with filters to remove fine particulate matter. Heating orcooling units may be present, employing heating coils or cooling watercoils, and two types of anodes may be used, i.e., soluble or insoluble(when insoluble anodes are used, the pH of the plating solutiondecreases along with the metal ion concentration, and in some platingbaths, a portion of the anodes are replaced with insoluble anodes inorder to prevent metal ion buildup or to reduce metal ionconcentration). See, e.g., Kirk-Othmer, Encyclopedia of ChemicalTechnology, 4^(TH) Edition, under the heading, “Electroplating”.

Because electroplating takes place at the exact molecular surface of awork, it is important that the substrate surface be absolutely clean andreceptive to the plating, generally requiring that substrates beingelectroplated be prepared prior to electroplating. In the effort to getthe substrate into this condition, several separate steps may berequired, such as soak cleaning, followed by electrocleaning, followedby rinsing.

Formulations of plating baths may be flexible in some systems and verysensitive to variations in others, many of the more recent changesresulting from waste treatment and safety requirements. Besides theability to deposit a coating having acceptable appearance and physicalproperties, the desired properties of the plating bath include: highmetal solubility, good electrical conductivity, good currentefficiencies for anode and cathode, noncorrosivity to substrates,nonfuming, stable, low hazard, low anode dissolution during down-time,good throwing power, good covering power, wide current density platingrange, ease of waste treatment, and economical to use. Few formulas haveall these attributes, with only a few plating solutions being usedcommercially without special additives, to brighten, reduce pitting,and/or otherwise modify the character of the deposit or performance ofthe solution to meet some of the criteria above, with the suppliers ofthe proprietary additives normally specifying the preferred formulationsto be used.

Purification, often needed once a plating bath is prepared, is usedperiodically to maintain the plating solutions Alkaline zinc platingsolutions are sensitive to a few mg/L of heavy-metal contamination,which may be precipitated using sodium sulfide and subsequently filteredout. Nickel plating solutions may contain excess iron, which may beremoved by a process involving peroxide oxidation, precipitation at a pHof about 5, and filtration of the iron. The more complex, lesswater-soluble organic contaminants, along with some trace metals, areremoved with activated carbon treatments in separate treatment tanks. Acommon purification treatment used both on new and used platingsolutions is dummying, in which heavy-metal impurities are removed byelectrolyzing before the main electrodeposition step, usually at lowcurrent densities, using large disposable steel cathodes, good agitationand lower pH speeding the process. Once the heavy metal impurities havebeen electroplated onto the disposable steel cathodes, those cathodesare removed and new cathodes are placed into the acid electrolyte sothat the electroplating of the desired metal can be performed.

Relatively simple analyses and testing, requiring little equipment arerequired whenever a new plating solution is made up, and thereafter atperiodic intervals. Trace metal contaminants may be analyzed by usingspot tests, colorimetrically, and with atomic absorptionspectrophotometry. Additives, chemical balance, impurity effects, andmany other variables are tested with small plating cells, such as HullCells.

The precise makeup of plating bath compositions depends on the metalbeing plated. For example, cyanide copper plating baths typicallycontain copper metal, copper cyanide, potassium cyanide, potassiumhydroxide, Rochelle salts, and sodium carbonate, while acid copperplating baths (i.e., with sulfuric acid) typically contain copper metal,copper sulfate, sulfuric acid, and various additives, and watts nickelplating baths (with sulfuric acid) typically contain nickel metal,nickel sulfate, nickel chloride, boric acid, and various additives,while sulfamate nickel plating baths contain nickel sulfamate instead ofnickel sulfate.

Electroforming is the production or reproduction of articles byelectrodeposition upon a permanent or expendable mandrel or mold that issubsequently separated from the electrodeposit, with the electrodepositbecoming the manufactured article. Of all the metals, copper and nickelare the most widely electroformed metals.

A problem common to all of the above electrolysis procedures is thepresence of mist- acidic or alkaline- generated above the electrolytesolutions. Such mist is a severe health hazard and causes corrosion ofthe plant facilities and operating equipment. In order to reduce thequantity of mist, anti-misting agents (also referred to as demisting andmist-suppressing agents) are commonly added to the electrolytesolutions. However, the currently-available anti-misting agents are notcompletely satisfactory, due to limited demisting ability, high lossrate of such anti-misting agents, interference with the electrolysisprocess, and/or ecological incompatibilities. In the case ofelectrowinning, acid mist is particularly noteworthy and troublesome,and the use of mist-suppressing agents can interfere with the relatedextraction process (e.g., due to partial solubility of these agents inthe organic extraction solution, promotion of emulsion formation,promotion of slow phase separation, and interference with extraction orstripping kinetics). In addition, foaming may also be a significantproblem.

Tjernlund, D. M., et al., in “A Study of the Fire and Explosion HazardsAssociated with the Electrowinning of Copper in Arizona Surface MinePlants”, Section 8, U.S. Department of Labor, Mine Safety and HealthAdministration, Investigative Report, March 1999, report on theformation of acid mist in electrowinning as follows: “Oxygen bubblescreated at the anode rise to the surface of the electrolyte. At thesurface, these bubbles [which consist of oxygen surrounded by acidelectrolyte] expand above the liquid and then break, releasing entrappedoxygen into the atmosphere. The liquid in the bubble wall just before itbreaks is made up of the acid electrolyte solution. As the liquid wallof the bubble ruptures, it disintegrates into extremely small dropletsthat readily become airborne. The macroscopic effect of this process isto create an acrid acid mist above the cells. This mist readily migratesthroughout the workplace and represents a potential health hazard toworkers in the tankhouse. It also creates a corrosive atmosphere thatcan be detrimental to equipment and the tankhouse structure itself.”Under Section 8c, “Strategy 4: surfactants”, the authors go on: “In mosttankhouses, a water-soluble surface tension reducer is used todiscourage misting . . . . By lowering the electrolyte surface tension,the gas bubble wall becomes thinner when it reaches and protrudes abovethe electrolyte surface. This causes the bubble to break sooner withless generation of mist droplets”.

The authors note further that 3M's FC-100 and FC-1100 FLOURAD™ werecommonly-used anti-misting agents. They reported that FC-100 trapped therising gas in soapsuds-like bubbles above the surface, even at very lowconcentrations (a few hundred ppm). They note further, however, that theresulting foamy layer also created significant potential fire/explosionproblems. They concluded that the FC-1100 surfactant had significantlyless tendency to form suds than FC-100, but that, at higherconcentrations, it, too, generated an undesirable foam suds layer.

3M states that FC-1100 FLOURAD™ contains 45-55% fluorochemical solidsand 45-55% water and provides sulfuric acid mist suppression in thecopper electrowinning tankhouse without the formation of a stable foamblanket at the surface of the electrowinning cell. The exact nature ofthe fluorochemical solid is not disclosed.

C. Y. Cheng et al, “Evaluation of Saponins as Acid Mist Suppressants inZinc Electrowinning”, Hydrometallurgy, vol. 73 (2004), pp. 133-145,report on two saponins-rich products (MISTOP® Quillaja saponaria extractand QLZINC®, a commercial licorice product in zinc electrowinning testmodels) and include the use of MISTOP® saponins in a commercial copperelectrowinning operation. The authors report that saponins (highmolecular weight glycosides of steroids, steroid alkaloids ortriterpenes found in plants, consisting of a sugar moiety linked to atriterpene or steroidal aglycone, often referred to as nonrefinedQuillaja extracts) are natural surface-active compounds that give stablefoams in aqueous solutions.

U.S. Pat. No. 6,833,479 B2 (Witschger et al, the '479 patent),incorporated herein by reference in its entirety, discloses anti-mistingagents that are alkoxy-capped amine and trialkylol compounds having thestructure: R((AO)_(n)H)_(m)H_(p) (formula (a)), wherein each AO groupis, independently, an alkyleneoxy group selected from ethyleneoxy,1,2-propyleneoxy, 1,2-butyleneoxy, and styryleneoxy groups; n is aninteger of from 2 to 100; m is an integer of from 1 to the total numberof —OH plus —NH hydrogens in the R group prior to alkoxylation; the sumof m plus p equals the number of —OH plus —NH hydrogens in the R groupprior to alkoxylation; and the R group is a group selected fromcompounds of nine formulas, of which two of them are: N(CH₂CH₂O)₃ (b)and CH₃CH₂C(CH₂O)₃ (c). Otherwise, the R group of four other formulasrepresents amine derivatives, as exemplified by formula (b) above; the Rgroup of another formula represents alkoxylated trimethylol-ethane or-propane compounds, as exemplified by formula (c) above; the R group ofstill another formula represents alkoxylated pentaerythritols; and thefinal R group alternative represents alkoxylated phenylenediamine.

In testing, however, the monoethanolamine derivative of theparticularly-preferred triethanolamines of formula (b) of thisreference, when they contain six propylene oxide groups and elevenethylene oxide groups showed unacceptable interference with the copperelectrowinning process, in that, with its use, nodules formed on thenecessarily-smooth surface of the cathode. Nodule formation isparticularly undesirable, as nodules can grow to the extent that theyphysically touch the anode, resulting in a direct electrical short inthe electrowinning cell, and/or they tend to promote the entrapment ofimpurities in the copper deposited on the cathode, resulting in poorerquality of the recovered copper.

Additionally, test work carried out with another compound of the '479patent showed that approximately half of that anti-misting agent wasextracted from the aqueous phase into the organic phase duringstripping, potentially resulting in a buildup of the surfactant in theorganic phase and eventual phase separation problems. The presence ofthese particular surfactants also adversely affected extractionkinetics. In view of these negative impacts, these types of anti-mistingreagents are unacceptable for use in systems involving copper solventextraction followed by electrowinning.

In addition, U.S. Pat. No. 4,484,990 (Bultman et al) discloses the useof cationic or amphoteric fluoroaliphatic surfactants as anti-mistingagents in the electrowinning of metals in an acidic electrolyte, whereinall of these agents contain perfluoroalkyl chains and at least onelinking group (e.g., —COO—, —SO₃—, —OSO₃—, —PO_(3H)—, —OPO₃H—, or anammonium group). Functionalized perfluoroalkyl compounds, however, havecome under increased scrutiny by the EPA due to their impact on humanhealth and the environment.

Also, U.S. Pat. No. 4,770,814 (Rose et al) discloses the use ofamphoteric surfactants containing a long-chain (C₁₃-C_(1s) hydrocarbons)hydrophobic moiety for the reduction of mist generated by agitation,impact, or spraying, but the use of amphoteric compounds containinghydrocarbon chains, where the chain length is 12 or greater, have beenshown to severely impact the solvent extraction/electrowinning circuitby resulting in the formation of a stable emulsion at theorganic/aqueous interface.

Extensive research has been devoted to reducing the mist during theelectrowinning, electroplating, and electroforming processes, especiallyin electrowinning processes in which aqueous acidic electrolytesolutions of metal ions are typically used in the electrowinning step.By far the most common solution is to add an anti-misting agent toreduce the mist. However, the currently-available anti-misting agentsare not completely satisfactory, there still being a need for improvedanti-misting agents that: are ecologically compatible; are effectiveeven at low concentrations; have a low loss rate; are compatible withthe other plating bath chemicals and additives; and yet, do notinterfere with the kinetics of metal stripping or phase separation inthe metal recovery process if the anti-misting agent is present duringthese steps.

Thus, there still exists a need for improved anti-misting agents forelectrolysis/electrodeposition, particularly for use in theelectrowinning of copper.

BRIEF SUMMARY OF THE INVENTION

Improved anti-misting agents for the control of mist- acidic oralkaline- generated above electrolyte solutions during theelectrowinning, electroplating, and electroforming of metals have beenfound that are sulfonate-, sulfate-, or carboxylate-capped, alkoxylatedcompounds of the Formula: R((AO)_(n)B)_(m)((AO)_(n)H)_(p) (I),

-   -   wherein each AO group is, independently, an alkyleneoxy group        selected from ethyleneoxy (“EO”), 1,2-propyleneoxy (“PO”),        1,2-butyleneoxy, and styryleneoxy groups, preferably EO or PO;    -   n is an integer from 0-to-40, preferably 2-to-30, more        preferably 2-to-20, and most preferably 2-to-10;    -   m is an integer from 1 to the total number of —OH hydrogens in        the R group prior to alkoxylation;    -   p is an integer such that the sum of m plus p equals the number        of —OH hydrogens in the R group prior to alkoxylation;    -   B is SO₃Y, (CH₂)_(q)SO₃Y, CH₂CHOHCH₂SO₃Y or CH₂CH(CH₃)OSO₃Y,        where q is an integer from 2-to-4; and Y is a cation, preferably        a hydrogen, sodium, potassium or ammonium ion;    -   R is a group selected from Formulas (II)-(VIII):        R¹C(CH₂O)₃   (II),        -   where R¹ is H, methyl, ethyl, or propyl;            C(CH₂O)₄   (III);            OC(CH₂O)₂   (IV);            N(CH₂CH₂O)₃   (V);            (R²)_(x)N(CH₂CH₂O)_(y)   (VI),        -   where R² is a C₁-C₄-alkyl, y is 1-3, and x+y=3;            O(CH₂)_(r)O   (VII),        -   where r is 2-to-6; and            O(CH(CH₃)CH₂)O   (VIII).

It will be appreciated by those skilled in the art that the compounds ofFormulas (II)-(VIII) of the invention have differing kinds and variousnumbers of reacted alkyleneoxy moieties (i.e., the AO groups). This isdue to the method (i.e., polymerization) by which these compounds aresynthesized.

It will be further appreciated by the practitioner that the compounds ofFormulas (VI) and (VIII) may be capped at one or both ends. This occursbecause the degree of capping is not quantitative and the fully-cappedproducts are not isolated.

In another aspect, the invention includes aqueous electrolyte solutionscomprising an amount effective to suppress mist generated above suchelectrolyte solutions (preferably 2-to-100 ppm, more preferably 2-to-30ppm) during electrolysis procedures of one or more anti-misting agentsof Formula (I) above, in which all variables are as defined above,and/or Formula (IX):R³N⁺(CH₃)₂R⁴   (IX),wherein R³ is a group selected from Formulas (X) and (XI):C₆-C₁₂-alkyl   (X); andR⁵C(O)NH(CH₂)_(z)   (XI),

-   -   where R⁵ is a C₁-C₆-alkyl; and z is 2 or 3; and

R⁴ is a group selected from Formulas (XII) and (XIII):CH₂CO₂ ⁻  (XII); andCH₂CH(R⁶)CH₂SO₃ ⁻  (XIII),

-   -   where R⁶ is either H or OH.

In a further aspect, the invention includes a method for reducingmisting in electrolyte solutions containing metal ions by adding theretoa mist-suppressing quantity of one or more of the anti-misting agents ofFormulas (I) and/or (IX) above, in which all variables are as definedabove.

DETAILED DESCRIPTION OF THE INVENTION

Other than where otherwise indicated or understood, all numbersexpressing quantities of ingredients or reaction conditions used hereinare to be understood as modified in all instances by the term “about”.In addition, it is understood that the term “metals” also includesmetalloids.

In Formula (I) above, compounds that are fully alkoxylated arepreferred.

In Formula (II), when R¹ is methyl or ethyl, and in Formula (V), m ispreferably 1.5 to 3, more preferably 2 to 3.

The styryleneoxy groups may be unsubstituted, or may containsubstituents on the phenyl group, such as one or more C₁-C₆-alkylgroups, C₁-C₆-alkoxy groups, and/or other groups that will not interferewith electrolysis.

The compounds of Formula (II), in which R¹ is methyl or ethyl, i.e.,sulfonate- or sulfate-capped, alkoxylated trimethylol-ethane or -propanecompounds, are preferred compounds of the invention. Such compounds, inwhich AO is EO or PO, are preferred, and those in which AO is EO aremore preferred. Most preferred are the propane derivatives of Formula(II), in which R¹ is ethyl.

Electrolyte solutions containing, and methods of reducing misting inelectrolyte solutions by adding, either alone or in a mixture with oneor more compounds of Formula (I), one or more compounds of Formula (IX),in which R³ is represented by Formula (XI), R⁵ is preferably C₃-C₆alkyl, and z is preferably 2 to 3, more preferably 3, as well as thosein which the R³ group is represented by Formula (X), where R³ is hexyl,octyl, an octyl/decyl mixture, or decyl, and where the R⁴ group isrepresented by Formula (XII), are preferred.

The above alkoxylated compounds may be readily produced by alkoxylatingthe corresponding alcohols and/or amines by methods well known to thoseskilled in the art, e.g., by reacting the alcohols and/or amines withthe desired quantities of alkylene oxides.

The compounds in Formula (IX), in which the R³ group is represented byFormula (X), where R³ is decyl, and where the R⁴ group is represented byFormula (XII), may be readily produced by reacting a N,N-dimethyltertiary amine with either 1,3-propanesultone or with sodiumchloroacetate, according to standard techniques described in theliterature.

The anti-misting agents—the novel compounds and/or the compounds notpreviously known to be useful as anti-misting agents—according to thisinvention are useful in reducing or minimizing the misting problems thatmay be present in electrowinning compositions, electroplatingcompositions, and/or electroforming compositions and/or in proceduresthat utilize aqueous electrolyte solutions of metals ions or aqueouselectrolyte dispersions of metals in metallic form, as well as withwaste solutions containing dissolved metals. In all cases, it beingunderstood that the metals/metalloids may be present in ionic formand/or in elementary form. And in the electrolysis of metals fromaqueous electrolyte solutions containing the metal(s) to be captured,the utility of the compounds according to the present invention is notdependent on the particular metal(s) present in the electrolytesolutions.

The anti-misting agents of the present invention are effective inquantities as low as a few parts per million, based on the electrolytecomposition, e.g., from 2-to-100 ppm, preferably from 2-to-30 ppm, andmost preferably from 5-to-25 ppm. In an electrowinning application, theymay be added to the aqueous strip solution used in the stripping stagefollowing the solvent extraction stage, or to the metal-pregnant aqueoussolution that results from the stripping of the organic phase in thestripping stage, or, preferably, to the metal-containingelectrolyte/strip aqueous phase in the electrowinning tankhouse.

There are a number of electroplating methods for which the demistingagents of the invention may be used. Materials, such as strip steel, maybe plated in plating tanks where coils of steel are unrolled in acontinuous basis, fed through a series of preparation steps, and theninto the plating tank. Wire that is uncoiled from the spools or reels onwhich it was wound, may be passed through various processing steps andthen plated, with metals, such as copper, copper alloys, zinc, iron,iron alloys, nickel, nickel alloys, gold, or silver, as individualstrands. Stampings, moldings, and castings are typically mounted ontospecially-designed plating racks for electroplating. Small parts, e.g.,dipping baskets and plating barrels made of inert plastic materials, maybe electroplated using bulk plating methods. Where parts are large andonly smaller areas of the parts are to be plated, brush plating is used,i.e., using plating tools which are shaped anode materials covered withan absorbent material saturated with the plating solution.

Insoluble anodes are used exclusively in the plating baths of thepresent invention. Chromium plating solutions utilize lead-tin,lead-antimony, or just lead anodes; gold and other precious metalplating processes use stainless steel anodes, keeping inventory costsdown.

However, the use of insoluble anodes may, unfortunately, also result inside effects. In alkaline cyanide solutions, the generation and buildupof carbonates is accelerated as a result of the use of insoluble anodes,along with a significant reduction in alkalinity. In acidic solutions,the pH decreases, requiring frequent adjustments. In sulfamate nickelplating solutions, insoluble anodes, and even slightly passive solubleanodes, partially oxidize the sulfamate ion to form sulfur-bearingcompounds which change the character and performance of the deposit.(See Kirk-Othmer, supra).

Production of the Compounds of the Invention

The synthesis of the sulfoalkyl derivatives of the compound of Formula I(i.e., those in which B=(CH₂)_(q)SO₃Y) may typically be accomplished asa two-step reaction that may be performed in the same reaction vessel.The first step of the reaction involves the addition of sodium metal tothe alkoxylated polyol (i.e., one of the compounds from Formula(II)-(VI)) to form the corresponding terminal sodium alkoxide. Thesecond step of the reaction is the addition of 1,3-propane sultone tothe sodium alkoxide formed in the first step. Toluene (or other inertorganic solvent) is used as the solvent throughout the process.

The sulfonate-capped derivatives of the compounds of Formula (I) inwhich B=CH₂CHOHCH₂SO₃Y (2-hydroxypropanesulfonate) may also typically beaccomplished as a two-step reaction (known as a Williamson synthesis)that may be performed in the same reaction vessel, preferably in aninert organic solvent, such as toluene. The first step of the reactioninvolves the addition of sodium metal to the alkoxylated polyol (i.e.,one of the compounds from Formula (II)-(VI)), as above, in order to formthe corresponding terminal sodium alkoxide. The second step of thereaction is the addition of 3-chloro-2-hydroxy-1-propanesulfonic acidsodium salt to the sodium alkoxide formed in the first step, and theproduct is recovered by addition of water to the organic phase aftercooling. The aqueous phase is then isolated.

The production of the sulfate-capped derivatives of the compounds ofFormula (I), in which B=SO₃Y, may be accomplished by starting with thesame ethoxylated polyols (i.e., one of the compounds from Formula(II)-(VI)) described above and converting their terminal hydroxyl groupsto sulfates by reactions known in the art. Alternatively, the terminalhydroxyl may be capped by reacting them with allyl chloride, and thenadding sulfuric acid across the double bond to give a slightly differenttype of sulfate cap.

The alkoxylated compounds of Formula (I) above, may be readily preparedby alkoxylating the corresponding alcohols and/or amines by methods wellknown to those skilled in the art, e.g., by reacting the alcohols and/oramines with the desired quantities of alkylene oxides. Such synthesesare illustrated and/or exemplified in Synthetic Detergents, A. S.Davidsohn and B. Milwidsky, Seventh Edition, LongmanScientific andTechnical, 1987, pp. 178-191, and Kirk-Othmer, Encyclopedia of ChemicalTechnology, 3rd Edition, Volume 9, John Wiley and Sons, New York, 1980,p. 437, among other places.

The compounds of Formula (IX) are classified as betaines. The compounds,in which the R³ group is represented by Formula (XI) and the R⁴ group isrepresented by Formula (XIII), are called sulfobetaines betaines. Suchcompounds, where z=3, are called3-[(3-alkylamino-propyl)-N,N-dimethylammonio]-propane sulfonates or2-hydroxy-3-[3-alkylamino-propyl)-N,N-dimethylammonio]-propanesulfonates (if the R⁵ group is C₁, then replace “alkyl” with “methyl”;if the R⁵ group is C₂, then replace “alkyl” with “ethyl”; if the R⁵group is C₃, then replace “alkyl” with “propyl”, and so on) The firststep in the synthesis in both cases is the reaction of3-(dimethylamino)propyl amine with an ester under standardtransamidification conditions to generate the corresponding amide. Inthe second step, the resulting amide is reacted with either the1,3-propane sultone or 2-hydroxy-3-chloropropanesulfonic acid underconditions known in the art.

The compounds of Formula (IX), in which the R³ group is represented byFormula (X) and the R⁴ group is represented by Formula (XIII), areclassified as alkyl N,N-dimethylsulfonates. The synthesis of thecompounds is accomplished by the reaction of 1,3-propane sultone or2-hydroxy-3-chloropropanesulfonic acid with a N-alkyl-N,N-dimethyl aminein anhydrous acetone using, conditions known in the art.

These compounds of Formula (IX), in which the R³ group is represented byFormula (X) and the R⁴ group is represented by Formula (XII), areclassified as alkyl N,N-dimethylglycines. The synthesis of the compoundsis accomplished by the reaction of sodium chloroacetate with aN-alkyl-N,N-dimethyl amine in water. After the reaction is complete,there is no need to further purify of the product.

The invention is further illustrated, but not limited, by the followingExamples, the compounds for which were prepared by first reactingethylene oxide with triethanolamine, then reacting the resulting productwith 1,2-propylene oxide.

Example 1 Preparation of Sodium Sulfopropyl Etherate of Ethoxylated2-ethyl-2-(hydroxymethyl)propane-1,3-diol (Compound A)

To a 5000 mL round bottom flask equipped with a Dean-Starktrap/condenser/drying tube, a mechanical stirrer, and apressure-equalizing funnel, was added 199.5 g (0.45 mol)trimethylolpropane that has reacted with seven moles of ethylene oxideand 2.75-3 L of toluene. The solution was refluxed for four hours toremove any water (azeotrope using the Dean-Stark trap). The Dean-Starktrap was then removed, and the condenser was replaced with a drycondenser. The temperature of the reaction flask was kept at just therefluxing temperature of toluene (overheating causes the solution todarken considerably). To the reaction flask was then added 31.05 g (1.35mol, 1 mol equivalents to the hydroxyl groups of the trimethylolpropanecontaining seven ethyleneoxy groups) of sodium metal, washed with hexaneprior to use, over a one hour period. Addition of the sodium metalresulted in a substantial increase in temperature. The solution was thenstirred for four additional hours. While there was some sodium still inthe reaction vessel, it was completely consumed in the next phase of thereaction.

1,3-Propane sultone (165.0 g, 1.35 mol) was transferred to the additionfunnel along with 400 mL of toluene. The addition of the 1,3-propanesultone was performed over a 20-30 minute period. Addition of the1,3-propane sultone was carefully monitored because of the extremetemperature increase at the beginning of the addition, and the formationof an intractable solid at the end of the addition. The solution wasstirred as the 1,3-propane sultone was added, and continued to bestirred until the formation of the solid product caused the mechanicalstirrer to stop, then the toluene was decanted off while still hot. Toremove the solid, the contents of the flask had to be dried using avacuum pump and the solid broken apart with a steel rod. The solid wascollected, crushed, and washed with hot toluene. The crushed solid wasdried using a vacuum of 500 millitorr, and was pulverized using a mortarand pestle. The yields from three runs of this preparation were 95.45%,91.37%, and 97.8% respectively (this preparation is typical for FormulaI compounds).

Preparation of N-decyl-N,N-dimethylglycine (Compound E)

The following is a typical reaction for the synthesis of the alkylN,N-dimethylglycines. To a 500 mL flask 3 necked flask equipped with acondenser, a mechanical stirrer, and the other opening sealed with ateflon stopper was added 92.70 g N-decyl-N,N-dimethyl amine (0.50 mol)and 58.25 g sodium choloroacetate (0.50 mol) dissolved in 151.0 g ofwater. The solution was heated to 90° C. using a silicon oil bath.

The temperature was kept constant throughout the reaction using atemperature probe connected to the hotplate. The stirring rate was keptat 250 rpm throughout the reaction. After three hours a sample was takenand potentiometrically titrated with 0.1 M NaOH using standardtechniques. Since there was no free amine present (<1%) the reaction wasterminated. The yield from the reaction was quantitative. (thispreparation is typical for alkyl N,N-dimethylglycines.)

Example 2 Anti-Misting Capability

In order to demonstrate the anti-misting characteristics of theseproducts, two compounds of the invention: the tri-sodium sulfopropylether of trimethylolpropane containing seven ethyleneoxy groups(Compound A) and the tri-sodium sulfopropyl ether of triethanolaminecontaining six polyoxypropylene groups and eleven polyoxyethylene groups(Compound B) were tested against five hundred mL samples of copperelectrolyte solution (50 g/l Cu⁺², 0.2 g/l Co⁺², 1.5 g/l Fe⁺³, 170 g/lsulfuric acid) in a jacketed beaker controlled at 45° C., with mistbeing generated by passing air through a fine frit (4-8 micron)scintered glass bubbler in the copper electrolyte. The mist was sampledby suctioning air through a sampling tube 1.5 inches above the liquidlevel, the tube being connected to a water trap. At timed intervals, thewater from the trap was titrated with sodium hydroxide to a bromphenolblue endpoint to determine the amount of acid contained therein, theresults in the Table being calculated in millimoles of sulfuric acidcaptured per hour. The results of the anti-misting tests are shown inTable 1:

TABLE 1 Anti-Misting Concentration Compound A Compound B (ppm) (mmolH₂SO₄/hr) (mmol H₂SO₄/hr) 0 3.44 3.26 5 0.90 0.77 10 0.59 0.38 20 0.390.23 30 0.23 0.16 40 0.20 0.14

These results demonstrate that Compounds A and B of the inventionsubstantially reduce the level of mist to commercially-acceptableconcentrations.

Example 3 Copper Electrowinning Comparison

Three anti-misting agents according to the invention (Compound A [fromExample 2, where m is ˜3], the sodium sulfopropyl ether ofmonoethanolamine containing six propylene oxide groups and elevenethylene oxide groups, where m is ˜3 [Compound C] and monoethanolaminecontaining six propylene oxide groups and eleven ethylene oxide groupsreacted with only two moles of propane sultone for each mole of themonoethanolamine, where m is ˜2 [Compound D]) and monoethanolaminecontacted with six moles of propylene oxide and eleven moles of ethyleneoxide (Compound 1, the preferred embodiment from U.S. Pat. No.6,843,479), and a blank run with no anti-misting agents, were tested inan electrowinning apparatus with guar added as a smoothing agent. Thebasis for all three new molecules is either Compound 1 ortrimethylolpropane containing seven ethyleneoxy groups. The threeanti-misting agents according to the invention tested were:

The results demonstrated that Compound A provided a clean, even plate.The plate of Compound B was almost as good quality as that of CompoundA. However, the plate of Compound C showed that it had a slight tendencyto form nodules. Earlier testing demonstrated that the plate forCompound 1 contained substantial nodule growth which not only results ina poor plate quality for copper recovery, but also can produce hazardouselectrical conditions in the cell.

Procedure

For each 16-hour run, 35 L of electrolyte was prepared withconcentrations of 38 g/l Cu, 2 g/l Fe³⁺, 0.1 g/l Co, 0.01 g/l Cl, and175 μl H₂SO₄. This was accomplished by dissolving appropriate levels ofCuSO₄, Fe₂(SO₄)₃, CoSO₄, NaCl, and H₂SO₄ in deionized water. Eachsolution was then split into two 5-gal buckets to feed theelectrowinning for two days at eight hours each day.

An electrowinning cell, housing one cathode and two anodes, was madefrom PVC plastic and fitted with a water jacket in order that the cellcould be maintained at a given temperature. The cathodes were cut fromstainless steel with a surface plating area of about 3 in×3 in (0.0625ft² counting both sides) and a thickness of slightly less thanone-sixteenth inch; the anodes were lead plates and slightly smaller inwidth and height than the cathode. The electrolyte in the cell, whilerunning, measured 11 cm deep×8 cm wide×12.5 cm long, for a volume of 1.1L, and it was pumped into and out of the cell at a rate of 28 ml/min, inorder to achieve a 3 g/L drop in Cu concentration across the cell. Thecurrent density used in the experiments was 30 A/ft² (within the typicaltankhouse current densities of between 12 and 38 A/ft²), and based onthe surface area of the cathode, the current needed to flow to the cellwas calculated to be 3.75 A.

At the beginning of each test, 0.07 g (4 ppm) of Galactasol® 40H₄CD guargum derivative and 0.175 g (10 ppm) of the potential demisting agent forthat run were added, while stirring with an impeller, to one of the twobuckets containing the electrolyte. The jacket for the electrowinningcell was filled with deionized water and hooked up to a recirculatingwater bath in order to maintain the electrolyte in the cell at 45° C.The inlet tube for the cell was run through a peristaltic pump set to 28ml/min and placed into the bucket containing the spiked electrolyte,which had been warmed up on a hot plate to ˜45° C., with the exit tubebeing placed in a clean, empty 5-gal bucket. The 1200 ml of warmelectrolyte was added to the cell to fill it to the appropriate level(in order that the submerged area of the cathode was 0.0625 ft). Theanode and cathode were hooked up to a constant current power supply, andthe pump was turned on. Once the lines were full and the electrolyte wasflowing through the cell, the power supply was turned on and set to 3.75A continuous current.

This arrangement was run for eight hours before turning off the powersupply, the water bath supplying the jacket, and the peristaltic pump,and the wire to the cathode from the power supply was unhooked in orderto prevent current backflow. After allowing the cathode to sit in thebath overnight, the cathode was dried, weighed, and photographs weretaken of it.

The above procedure was repeated the following day with the second batchof tests solutions. Again, after allowing the cathode to sit in the bathovernight, the cathode was dried, weighed, and photographs were taken ofit.

The electrowinning tests for Compound A and Compound D (Compound C wasnot checked) were repeated in a 40-hour run in order to ensure noobvious negative characteristics of the copper deposit. Each 40-hour runrequired 70 L of electrolyte, split into five 14-L batches, each batchreceiving 0.056 g (4 ppm) of the guar polymer and 0.14 g (10 ppm) of thedemisting agent being evaluated. These runs confirmed that Compound Aproduces high quality plates and Compound D tends to produce plateshaving a limited number of small nodules.

Example 4 Effect on Copper Extraction Circuit Kinetics

The extraction circuit kinetics tests were run using the Cognis standardquality control test method in order to determine whether the testedanti-misting agents were too soluble in the organic phase or have anadverse effect on phase separation in the extraction stripping phase.

A 4-L batch of 10 v/v % LIX® 984N mixed ketoxime/aldoxime extractionreagents was made up in Conoco® 170Exempt aliphatic diluent. One-literof Cognis QC Electrolyte (i.e. solution contains 35±0.7 g/l Cu (as thesulfate) and 160±2 g/l H₂SO₄) batches (six in total) were spiked tolevels of 20 and 50 ppm (three with 20; three with 50), respectively,with each of Compounds A, C and D (from Example 3). One liter of QCElectrolyte, without any demisting agent, was run through the QC Test asa control batch. A 400-ml sample of the UK 984N reagent solution wascontacted with 400 ml of one of the electrolyte solutions for 3 minutesby shaking vigorously in a 1-L separatory funnel. The solutions wereallowed to separate, a sample of the equilibrated organic (E.O.) wastaken, and 350 ml of the organic was placed in a 1-L baffled beaker. Animpeller was lowered into the organic solution in order that the top ofthe polypropylene hub of the impeller was at the surface level of theorganic. The impeller was started up at 1750 rpm and 350 ml of a controlfeed (6.0 g/l Cu, 3.0 g/l Fe⁺³, pH=2.0) was added over five seconds. Asample of the emulsion was taken at 30 seconds to obtain a sample of theorganic (E30). The mixing continued for 300 seconds total at which timethe mixer was stopped. The time required for a complete separation ofthe phases was then determined (phase break time). A sample of theorganic after 300 seconds of mixing (E300) was then taken. The organicand aqueous phases were transferred to a 1-L separatory funnel andallowed to separate again. A 325-ml sample of that organic was placed ina 1-L baffled beaker and a clean impeller was placed at the same levelas the extraction test. The impeller was started up at 1750 rpm and 325ml of the same QC Electrolyte as the first contact was added over 5seconds. A sample of the emulsion was taken at 30 seconds to obtain asample of the organic (S30). The mixing continued for 300 seconds total,at which time the mixer was stopped, and the phase break time was thendetermined. A sample of the organic phase was then taken (S300), withthe results for the seven kinetics tests shown in Table 1.

TABLE 2 Kinetics Test Results Phase Assay E.O. E30 E300 S30 S300 Break(s) Blank Cu 1.42 4.72 4.75 1.64 1.63 95, 75 % E300 99.10% 99.68% 20 ppmCu 1.44 4.70 4.73 1.65 1.63 90, 55 Cmpd. C % E300 99.09% 99.35% 50 ppmCu 1.45 4.71 4.76 1.68 1.64  90, 110 Cmpd. C % E300 98.49% 98.72% 20 ppmCu 1.43 4.69 4.73 1.64 1.63 85, 80 Cmpd. A % E300 98.79% 99.68% 50 ppmCu 1.42 4.69 4.72 1.65 1.63 95, 75 Cmpd. A % E300 99.09% 99.35% 20 ppmCu 1.41 4.66 4.71 1.64 1.62 145, 95  Cmpd. D % E300 98.48% 99.35% 50 ppmCu 1.42 4.66 4.74 1.68 1.62 120, 150 Cmpd D % E300 97.59% 98.08%The above extraction circuit kinetics data demonstrates that Compound Aand Compound C do not have any substantial impact on the solventextraction performance. However, Compound D does appear to have a smallnegative impact on phase separation.

Example 5 Surface Tension Determinations

Surface tensions were measured on QC Electrolyte with Compounds A, C andD, FC1100, and Mistop at levels of 5, 10, 20, and 40 ppm. The resultsare shown in Table 3.

TABLE 3 Surface Tension Determinations Mist Suppressant ConcentrationSurface Tension (dynes/cm) (ppm) Cmpd. C Cmpd. A Cmpd. D FC1100 Mistop 076.7 76.7 76.7 76.7 76.7 1 — 63.7 60.7 53.7 64.6 5 64.4 61.6 62.4 58.562.0 10 61.5 59.8 61.8 61.4 58.3 20 62.4 63.5 59.9 59.5 61.7 40 60.054.7 58.0 54.3 59.5Based on the above surface tension comparisons, Compounds A, B, and Care equally effective in lowering the surface tension of the electrolyteas the commercially-accepted FC1100.

Example 6 Surface Tension Measurements of Compounds of Formula (IX)

Surface tension measurement of QC electrolyte containing variousconcentrations of anti-misting agents were performed as the reduction insurface tension is a good indicator of mist suppression behavior. Thesemeasurements were carried out utilizing a Fisher Surface Tensiomat 21 inmanual mode utilizing the du Nouy methodology (standard method). Resultsfor the most preferred compounds of the invention may be found in Table1; Compound E (N-decyl-N,N-dimethylglycine), Compound F(N-octyl-N,N-dimethylglycine), Compound G(N-dodecyl-N,N-dimethylglycine). FC-1100, from 3M, is the commerciallyaccepted anti-misting agent.

TABLE 1 Surface Tension Determinations Mist Suppressant ConcentrationSurface Tension (dynes/cm) (ppm) Cmpd. E Cmpd. F Cmpd. G FC-1100 0 62.063.5 61.3 61.3 10 46.4 49.4 41.2 42.0 20 43.2 46.5 40.9 40.7 30 41.143.7 40.5 40.8 40 39.9 43.2 39.9 39.3 50 39.5 41.9 39.4 37.0

Example 7 Anti-Misting Capability of Compounds of Formula (X)

In order to measure acid mist suppression of anti-misting agents ofFormula (In these compounds were added to an operating electrowinningcell. The electrolytic cell was made of 3/16″ thick Lexan plastic andmeasured 3.5″ in width, 8.5″ in length, and 6.5″ in depth. An overflowweir was placed near the exit side of the cell and measures five inchesin height. An entrance baffle, also 5″ in length, was placed near theelectrolyte entrance. Along the top of the cell, nine square-cut grooveswere cut to allow the anode and cathode busbars to sit on cell. Centered0.5″ beneath the 4^(1h) groove cut, a 5/16″ hole was bored out to serveas a sample port. Two 0.5″ holes were bored in the opposite ends of thecell to serve as feed entrance and exits. The entrance hole was bored at4.25″ from the bottom of the cell, and the exit hole was bored at 2.5″above the bottom of the cell. Teflon-taped fittings were screwed intothe ends to provide for tubing attachments.

Anodes and cathodes were cut in order to fit the electrowinning cell.Lead anodes were cut from 1/16″ thick lead sheet and measure 3″×5.25″.The anodes were attached to a copper busbar with two small threadedscrews and 12 Gauge copper wire was run between the two anodes inseries. The last anode was connected with 12 Gauge copper wire to thepositive terminal of the DC power supply. Cathodes were made from 1116″thick stainless steel 316 (SS316), and had the same dimensions as theanodes. Similarly to the anode, the cathode was attached to a copperbusbar with a threaded screw with 12 Gauge copper wire connectionsbetween cathodes. The busbar was connected to the negative terminal onthe DC power supply.

The collection of acid mist was accomplished by drawing the mist througha reservoir of water in an Erlenmeyer flask at a constant flow rate(1800 mL/min through a 1/16″ inlet nozzle). After a timed interval, thewater from the reservoir was titrated with a standardized sodiumhydroxide solution to a phenolphthalein endpoint. The amount of sodiumhydroxide used in the titration was then used to determine the relativeamount of acid mist.

Procedure:

Copper electrolyte was prepared in 40 L batches and included: 35 g/l Cu,2 g/l Fe³⁺, and 1780 g/l H₂SO₄. This was done by dissolving appropriatelevels of CuSO₄, Fe₂(SO₄)₃, and H₂SO₄ in deionized water. Analysis ofthe solution was performed prior to running by AAS. Approximately 15 ppmof GALACTASOL® 40H₄CD guar solution was added to the electrolyte forcathode smoothing purposes. An anti-misting agent was then added at theappropriate concentration, and the entire solution was thoroughly mixedprior to introduction into the EW cell.

The electrolyte was introduced into the electrolytic cell at a flow rateof 30 mL/min via a peristaltic pump. The electrolyte reservoir wasplaced in a re-circulating water bath in order to control thetemperature to between 40° C. and 42° C. A stir bar was placed in theelectrolytic cell to ensure proper mixing. Once the electrolyte hadreached 40° C., the DC power was turned on and voltage and amperageadjusted to give 4.10 A at 5.0 to 5.2 V. This should provide a currentdensity of 300 A/m², in a single-cathode arrangement. The electrolyticreaction was allowed to proceed for three hours.

After three hours, the sample probe and tubing were rinsed with a fewaliquots of DI water into the water trap to qualitatively transfer anyresidual acid on the interior surfaces of the probe and tubing. A fewdrops of phenolphthalein were added to the water in the Erlenmeyerflask. The acid mist/water sample was then titrated with standardized0.1 M NaOH. The endpoint of the titration is indicated by a change incolor of the solution from clear to pink. The amount of NaOH isproportional to the acid mist generated and the results of the analysisare shown in Table 2 for the most preferred betaines (Compounds E, F,and G).

TABLE 2 Mist Suppression Determinations Mist Suppressant ConcentrationAcid Mist (mL of 0.1M NaOH titrant) (ppm) Cmpd. E Cmpd. F Cmpd. GFC-1100 0 5.06 4.98 5.06 5.06 10 2.44 3.66 2.32 1.82 20 2.21 3.04 2.151.67 30 1.96 2.46 1.90 1.71 40 1.94 2.28 1.35 1.76 50 NA 2.42 0.58 0.40

Mist values for the 40 and 50 ppm concentrations of Compound G in Table2 were very low due to foaming on the surface of the electrowinningsolution. At no other time was any foaming noticed for the othercompounds in the electrowinning trials at concentrations up to 100 ppm.

Example 8 Effect of Anti-misting Agent on Extraction Circuit Kinetics ofCompounds of Formula (IX)

Extraction circuit kinetics were obtained using a two extraction/onestrip stage (2E/1S) circuit in order to determine whether theAnti-misting agents had a negative effect on the organic phase or thephase separation times. The counter-current 2E/1S system was comprisedof Lexan mix boxes (180 mL capacity), each containing an impeller mixerwhich agitates the solution in the mix-box portion of the stage. Theresidence time of the cell was 180 seconds. The impellers were run at1750 rpm and the continuity of the system was kept organic continuous.

Initial levels of pregnant leach solution (PLS), strip electrolyte (SE),and loaded organic (LO) were added to the appropriate mix boxes. Aninitial equilibrium was established with the organic by pre-contactingfresh organic reagent with strip electrolyte prior to addition into thecircuit. PLS was fed into the system at a rate of 15 mL/min. Organic(either 10% v/v or 30% v/v LIX® 984N in Shellsol D70) was pumped from anoverflow surge tank into the circuit at a rate of 30 mL/min. Stripelectrolyte was also pumped in at a rate of 30 mL/min. All circuitstages were kept at ambient temperature with the exception of the stripstage. The strip stage was heated to between 40° and 42° C. The circuitwas run for a minimum of 24 hours of operation.

Synthetic electrolyte (˜35 g/L Cu, 2 g/L Fe³⁺, 180 g/L H₂SO₄, 15 ppmguar) was pre-dosed with a specific concentration of mist suppressant.As this solution was run through the circuit, samples were taken todetermine if there were any issues with kinetics or circuit metallurgy.Overall organic entrainment and phase-break times were determined forthe two LIX® 984N concentrations (10% and 30%). Samples were taken afterapproximately 24 hours of total circuit run time and analyzed for metalconcentrations in the various circuit operations (Strip, E1, E2,Raffinate streams). The results of the analysis may be found in Table 3.

The only negative impact on solvent extraction by the most preferredanti-misting agents (Compounds E, F, and G) occurred when using CompoundG. At low concentration (10 ppm), Compound G was noted to cause a stableemulsion layer to form in the strip stage. This emulsion layer did notbreak and was stable for well over 24 hours, filling the settler boxnearly to its full depth. No emulsion layers were noted with Compounds Eor F at any dosage concentration. Entrainments for Compounds E or F werein the 100-300 ppm range, which is consistent with industrial levels.All other results in Table 3 are consistent with normal operatingvalues.

TABLE 3 Circuit Results 10% LIX ®984N 30% LIX ®984N 10% LIX ®984N 30%LIX ®984N 10% LIX ®984N Circuit 30 ppm Cmpd E 30 ppm Cmpd E 30 ppm CmpdF 30 ppm Cmpd F 10 ppm Cmpd G Operation Cu (g/L) Fe (ppm) Cu (g/L) Fe(ppm) Cu (g/L) Fe (ppm) Cu (g/L) Fe (ppm) Cu (g/L) Fe (ppm) E1 3.11 1.407.79 8.68 3.17 1.70 7.55 10.81 3.11 1.40 E2 1.60 2.90 5.05 7.02 1.563.00 5.05 7.97 S1 1.52 0.28 4.92 0.62 1.47 0.30 4.82 0.84 Feed 3.08 2.407.91 8.84 3.16 2.20 8.01 10.14 3.13 2.30 Raffinate 0.09 3.01 0.12 3.120.10 3.63 0.11 3.43 0.12 3.33 Rich Electrolyte 39.69 2.02 40.12 2.3138.42 2.33 39.54 2.81 Lean Electrolyte 36.61 1.95 35.96 1.86 36.20 2.2236.76 2.06 PLS 1.39 2.98 1.41 1.41 1.39 2.98 1.41 1.41 1.37 2.87 AqeousBreak 53 sec 64 sec 48 sec 74 sec  75 sec Organic Break 68 sec 89 sec 73sec 80 sec >300 sec Entrainment 137 ppm 317 ppm 167 ppm 334 ppm NA

Example 9 Copper Quality of Compounds of Formula (IX)

Copper was plated for 8-22 hours using the same conditions as describedin Example 1 in order to inspect the quality of the copper deposited.The quality of the cathode was determined by a visual inspection usingmicroscopy at low power (approximately 125× magnifications). The cathodeproduced using Compounds E, F, G and FC-1100 was of high quality and hadessentially smooth plates with little to no nodulation.

What is claimed is:
 1. An anti-misting compound of formula (I):R((AO)_(n)B)_(m)((AO)_(n)H)_(p), wherein each AO group is,independently, an alkyleneoxy group selected from ethyleneoxy,1,2-propyleneoxy, 1,2-butyleneoxy, and styryleneoxy groups; n is aninteger from 2-to-15; m is from 1 to the total number of —OH hydrogensin the R group prior to alkoxylation; p is an integer such that the sumof m plus p equals the number of —OH hydrogens in the R group prior toalkoxylation; B is SO₃Y, (CH₂)_(q)SO₃Y, CH₂CHOHCH₂SO₃Y, orCH₂CH(CH₃)OSO₃Y, where q is an integer from 2-to-4, and Y is a cation;and R is compound selected from:N(CH₂CH₂O)₃   (V);(R²)_(x)N(CH₂CH₂O)_(y)   (VI); where R² is a C₁-C₄ alkyl, y is a numberfrom 1-to-3, and x is a number such that x+y=3.
 2. The anti-mistingcompound according to claim 1, wherein R is the compound of formula (V),and m is 1-to-3.
 3. The anti-misting compound according to claim 1,wherein AO is selected from ethyleneoxy, 1,2-propyleneoxy, and mixturesthereof.
 4. The anti-misting compound according to claim 3, wherein AOis ethyleneoxy.
 5. The anti-misting compound according to claim 1,wherein Y is a hydrogen, potassium, sodium or ammonium cation.
 6. Anaqueous electrolyte solution containing: A) a metal, selected from thegroup consisting of copper, nickel and zinc, in ionic or dispersedmetallic form; and B) an amount effective to inhibit mist formation fromthe electrolyte solution of one or more anti-misting compounds offormula (I):R((AO)_(n)B)_(m)((AO)_(n)H)_(p)  (I) wherein each AO group is,independently, an alkyleneoxy group selected from ethyleneoxy,1,2-propyleneoxy, 1,2-butyleneoxy, and styryleneoxy groups; n is aninteger from 0-to-40; m is an integer from 1 to the total number of —OHhydrogens in the R group prior to alkoxylation; p is an integer suchthat the sum of m plus p equals the number of —OH hydrogens in the Rgroup prior to alkoxylation; B is SO₃Y, (CH₂)_(q)SO₃Y, CH₂CHOHCH₂SO₃Y,or CH₂CH(CH₃)OSO₃Y, where q is an integer from 2-to-4, and Y is acation; and R is compound selected from:N(CH₂CH₂O)₃  (V);(R²)_(x)N(CH₂CH₂O)_(y)  (VI), where: R² is a C₁-C₄ alkyl, y is a numberfrom 1-to-3, and x is a number such that x+y=3.
 7. The aqueouselectrolyte solution according to claim 6, wherein the anti-mistingcompound is present in an amount of 2 to 100 ppm based on theelectrolyte composition.
 8. The aqueous electrolyte solution accordingto claim 6, wherein the anti-misting compound is present in an amount of2 to 30 ppm based on the electrolyte composition.
 9. The aqueouselectrolyte solution according to claim 6, wherein the anti-mistingcompound is present in an amount of 5 to 25 ppm based on the electrolytecomposition.